Bonding of cast iron-aluminum in bimetallic castings by high-pressure die casting process

Abstract

A practical bimetallic casting consisting of aluminum matrix and cast iron inserts was manufactured via high pressure die casting (HPDC) process. Different surface treatment methods of the cast iron inserts, including salt membrane plating and electrogalvanizing, were adopted to improve the bonding quality of bimetallic castings. Microstructure characterization on the bonding interface was conducted at different locations of bimetallic castings. Results indicate that compounds with awless and continuously metallurgical bonding interface can be successfully fabricated by the HPDC process with the zinc rack plating treatment on the surface of cast iron inserts which results in a dense zinc coating with an average thickness of 8 μm. The melt ow speed and heat transition during solidi cation of the HPDC process are two key factors in determining the bonding integrity of bimetallic castings. With the dissolution and diffusion of the very thin zinc coating during solidi cation, there is no obvious aggregation of zinc element at the metallurgical bonding interface. Instead, a reaction layer with an irregular tongue-like morphology is formed with an average thickness of approximately 1 μm while it mainly consists of intermetallic phases Al 60 Cu 30 Fe 10 and Al 2 FeSi, etc.

(Sub)structure Development in Gradually Swaged Electroconductive Bars

“…The microstructure, which encompasses the overall properties of grains and includes their morphology, size, and type of boundaries, plays a crucial role in determining the behaviors and properties of a given metallic material [1]. Currently, the majority of metallic materials are prepared via either methods based on bulk casting [2][3][4] or techniques based on the processing of metallic powders (e.g., mechanical alloying [5,6], cold and hot sintering [7,8], selective laser sintering (SLS) [9,10], powder bed fusion (PBF) methods [11,12], and more). In order to enhance the microstructures of cast/sintered workpieces, deformation processing can be employed as an additional production step.…”